1. Field of the Invention
The present invention relates to lamps and lighting systems including floodlights, spotlights and the like.
2. The Prior Art
Incandescent reflective lamp assemblies known as floodlights and spotlights have been in universal use for many decades, their outputs directed according to their mounting in recessed ceiling fixtures or as adjusted in their swivel arrangements. Floodlights broadcast light evenly and widely whereas spotlights direct light in a smaller dispersion pattern with emphasis on a brightly illuminated center area known as a spot.
Recessed ceiling light fixtures are sometimes known in the trade as "highhats" while swiveled light fixtures are entirely exposed and are commonly called tracklights. The advent of small fluorescent tubing, known as compact fluorescent (CFL), in the 1980's allowed designers to enclose fluorescent technology within assemblies small enough to be installed in fixtures originally meant for incandescent flood/spotlights. Representative lights in the market in the United States are designated first by a letter(s) describing their shape followed by a number designating their diameter in one-eighths of an inch. Hence a PAR 38 lamp is a Parabolic Aluminized Reflective lamp four and three-quarters inches in diameter; an ER 40 would be an Ellipsoidal Reflector lamp five inches in diameter. In both of these examples, the light (lumen) output will vary by design according to a range of designed-in wattages varying by hundreds of watts.
In my copending patent application Ser. No. 08/302,469, there is a discussion of details prior art for reflective compact fluorescent (RCFL) lamps (i.e. U.S. Pat. Nos. 4,199,708, 4,833,574, 5,130,910, 4,723,200) that may in some cases replace incandescent flood/spotlight lamps, perhaps within the fixtures originally intended for the incandescents. Relamping with nine watt to twenty-six watt CFLs has been widespread, yet leaving much to be desired in five major areas.
The first and second major areas, weak lumen output and excessive outline dimensions, have been addressed my application Ser. No. 08/302,469, which discloses an invention that details differently shaped and oriented CFL tubing realizing dramatically high lumen output along with a finished assembly to match incandescent flood/spotlight spatial outlines. The reflective compact fluorescent (RCFL) lamp disclosed in the application solves these generalized performance and fit factors.
The third major area of needed improvement for RCFLs is with regard to their aesthetic distribution of light. Incandescent flood/spotlights utilizing small tungsten filaments positioned within parabolic or ellipsoidal reflectors easily direct light to achieve "pools" of light or desired "highlighting" of merchandise in retail stores. By contrast, CFL tubing, inherently requiring high amounts of surface area for fluorescing powders, cannot be focused to create the desired brighter center areas of light. For instance, though generally acceptable light levels are realized with CFL relamping in hotel lobbies, readability of newspapers may be sacrificed in the process without the focused light formerly provided by the original incandescents.
A fourth requirement for many users of recessed or track flood/spotlights is the capability of the lights to be dimmed for various purposes. Dimming of incandescent reflector lamps is easily and effectively accomplished by economical dimmer controls, sometimes called rheostats. As voltage to the incandescent light is lowered by the dimmer control, less amperage is drawn by the filament with a resulting lowering of emitted light. No harm is done to the incandescent lamp and its life is usually extended. Single, or multiple incandescent lamps on one circuit, are dimmed by a single inexpensive voltage control with no risk to the lamps. By contrast, CFLs and RCFLs, whether screw-in or handwired, have shown themselves to be extremely difficult and costly to be dimmed. Simple relamping, without adding additional system-wide wiring infra-structure, cannot achieve fluorescent dimming.
There are several reasons that dimmable retrofit RCFLs, whether screw-in or otherwise, are not in widespread consumer use. For a CFL to be dimmed without deterioration of its electrode elements, low voltage must be supplied and maintained to the elements to keep them heated while lamp arc voltage is reduced by another set of ballast connections. Only rapid-start type fluorescent lamps with four-pin two-circuit bases are capable of this, with the additional electrical system requirement demanding two separate voltages to be independently supplied to the original screw-in receptacle or hardwired fixture. New construction of buildings may include these two separate circuits at a reasonable cost, but this practice to date is virtually unimplemented. For the hundreds of millions, perhaps billions, of flood/spotlight fixtures in existing commercial buildings, retail stores and malls, and homes, retrofit of low voltage supply lines is financially prohibitive. Additionally, as dimmable rapid-start elements require constant amperage to keep them heated, even in the non-dimming mode, wattage is consumed and wasted with no gain in lumen output. As a significant secondary effect, this constantly heated filament technology also incrementally increases building air conditioning loads and costs.
A fifth area needing improvement for retrofit and new building RCFLs is higher reliability of even starting, and consequently, life expectancy of the lamp, under cold weather conditions. Flood/spotlights, in particular, are commonly used in conditions exposed to outdoor ambient temperatures. Many of these installations are in exterior walkways, hotel entrances, unheated garages, industrial sites, home and commercial security areas, and the like. Manufacturers of CFL products routinely warn against use of CFLs at temperatures from 32.degree. down to 0.degree. F. depending upon the manufacturer. Not being able to start at all is one problem, and at critical temperatures the high voltage arc will sputter and try to establish a mercury vapor in vain--the result being either an extremely shortened life of the lamp, or outright permanent failure. Incandescent, including (tungsten) halogen lamps are proven in extreme cold, in fact their hours of life are extended by the cold. Fluorescent technology, including CFLs, have been unable to match incandescents in this respect.